Telephone system



H. J. HERINK.

TELEPHONE SYSTEM.

Arme/umn msn Nov. lo. |916.

Patented Aug. 1, 1922.

6 SHEETS-SHEET H. 1. HEHINK.

TELEPHONE SYSTEM.

APPLICATION min Nov. lo. 1916.

6 SHEETS-SHEET 3.

Patented Aug. 1, 1922.

H. l. HERINK.

TELEPHONE SYSTEM.

APPLICATION m50 uov.1o.l191s.

H. l. HERINK.

TELEPHONE SYSTEM.

APPucATmN msu nov. lo. 191s..

Patented Aug. 1, 1922.

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g g." S JMS@ r www W yH. L'HEmNK. TELEPHONE SYSTEM. APPLICA-TIG FILED NOV.10| 1916.

Patented Aug. 1, 1922.

6 SHEETS-SHEET 5.

H. l. HERNK.

TELEPHONE SYSTEM.

APPLlcATloN FILED nov. 1o. ms.

1 ,424,644, Patented Aug. 1, 1922.

6 SHEETS-SHEE 6.

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HENRY JAMES HEEINK, 0F LONDON, ENGLAND, ASSIGNOR T0 THE RELAY 4AIU'T()M.,'.'l`.i(`}

' TELEFHONE COMPANY, LIMITED, OF LONDON, ENGLAND.

TELEPHONE srsrnivi.

Specification of Letters Patent;

Patented Aue. 1` 1922.

application ined November io, isis. semi ne. 130,551.

Tollwllwnimay concern:

Be it known that I, HENRY Jaime Hnarnn, -a subject of the King-of Great Britain, residing at Marconi House, Strand, London, England, hte invented newl and use iil proveniente in Telephoner Systems, lof which thev following is a s ecification.

The invention 're tes to automatic and semi-automatic telephone systems, and more particularly to systems of the lcind' in which thesubscribers ,of 'an automatic exchange are able to establish connectionsv over 'automatic switches, both with other subscribers 'und with an operator for enquiry purposes or for lthe extension of the connection to a trunk or, other line. A mon ,the enquiry 4 urposes may be included cal .which will ecome connected to an operator or operators position owing to a calling subscriber calling in a group in which no subscribers lines are connected or calling a subscribers number from which the'line has been purposely disconnected or the like. v

The object of the inventfon is so to 'arrange the circuits that the sameconnectinv apparatus and junction lines maybe both for connection between two subscribers and between a subscriber audanoperator, with the difference,- however, that when an `operator is called, current feeding bridge controlling relays and condensers associated with a junction line are automatically disconnected from the line, the subscriber being supplied with 4current from theoperators cord circuit, and the control Aof .the circuit being transferred to the operator.

Another object o' the invention is so to arrange the circuits that other operations such as metering, disconnectin and controlling supervisory si nelsr and jcruninatmg tones, may be per ormed according to the class of connection established.

The invention also relateslto calls to be completed by an operator with the object of setting up a connection with any subscrber connected to the automatic or semiautomatic system.

In a system according to this invention, a calling subscriber is normally. supplied with current from the junction line leading to the first digit Selecting stage, while the called subscriber receives current either from the Ysaine stage or from the inal connecting stage, the subscribers metering being carried out in any known manner.

According to the resent invention, the junctions 'have associated with themdiscriminating means, which, upon aconnection being established with amanual switchboard, are operatedlso as to clear the line from certain apparatus connected thereto and to cause circuit changes whereby the control of thelconnection, including release and metering, is transfer-red to 'the operator. The manual board may be located at the same 0r at a distant exchange.

The discriminating means are also operated in a manner dependent upon the successful completionof a call toano'ther subscriber, in order to cause meterin either immediately the required subscriber ifts the receiver or at the conclusion of conversation, be ore concurrently with, or afterrelease of the connecting` junctions.l The junctions from the ,manuali switchboard terinmate at theV automatic first di it switchin stage, andmeans are provi ed for enab ing the operator to obtain access to any "subscriber and toestablish a clear connection between the operators cord circuit with bridges, condensers `and otherV apparatus removed 'frcm thegjunction circuit.

The discriminating lmeans may'bea relay, or .relay arrangement capable of bein operated over the connection at. di erent sta es. i i

4urther features of the-invention will be described in connection with the accompanying drawings in which Figure vQL 1shows that part of a talking connection which is aociated with the subscribers line and the junction to the pre-digit sta e with the principal circuits of a set of re ay combinations according to part of the invention,

Figure 2 shows that part of a talking connection which is associated with the final or connector endr of 'checircuit Fi ure 2^ shows the modification necessary 1n Figure 2 if the operator is required to meter a cal-l completed by her.

Fi ure 3 shows that part of a talkin circuit (together with its associated relays which is connected either to Figure 1 or Figure 2, when a call is made to an operator.

. scriber 'that with little modification this This part of the circuit may be directly connected as a junction leading from any of the digit sta es, in which case Vit will be connected direct y to Fi re 1 when talking, or it may be connectingu subscribers line, in which case it Will when talking be connected to the s line over Figures 1 and 2 connected to ther. Y

vigure 4 shows that part of the talkin circuitA which is associated with the caller subscribers line, and is, when talking, attached to Figure 2.

Figure' 5 Vshows a cord circuit, which, when acall. is answered'by an operator, is connectedto Figui-e3. 4

Figure 6 shows another arrangement but similar in its operation to Figure 1. t

Figure fis similar to Fiv e 2 but iedesi ed to co-'operate with g 4iguie 6..

igure 8 is similar-to Fi ureV but 'is designed to co-operate with igures 6 4and-'7. It is also designed to be connected to the termination .of ajunctionifrom a. digit stage. It is obvious to anyone, skilled in the art art of the invention mightbeconnected tot e ordi' nary subscribers line equipment as in the case of Fi e 3.- A

The cor `circuit to be used with Figure 8 is one similar to that shown in Figure 5.

Figure 9 is another illustration of the invention and is used similarly to Fi res 1 and 6. Two rela s are shown each a tached to one line brano of the t circuit to effect thecircuitrch Laocor to the class' o. connection established. ese vrelays are used-to feed the called subscriber with talkin' `current on such a connection.

Figure 1 resembles 2 and 7 but is adapted tc'cdqaratey with Figure 9.

Figure `11 resem lea-Fi es 4 and 8 but is used with Figures 9 an 1 0.

Figure 12 illnstrates'a circuit to which are connected those lines purposely disconnected from the ordinary equipment. When a subscriberA calls .for one Yof these lines, the

line calling is connectedto the circuitshown over Figures l and 2,V Figures 6 and 7, or Fi res9and10. Y

i Ires 13 and 14 illustrate the circuit for tg; junctions connected from the manual switchboard to the first digit switching stage, so that an operator may obtain accesto any of the automatic subscribers.

Figures 3, 8 and 11 may be connected to levels at any stage in whichthere are no further junctions or subscribers lines, so that subscribers callin into these levels are connected to the circuit in a known manner, the release and the like being controlled as hereinafter described.

In yFigure l, LR and .COR are the line and cut olf relays respectively usually particular to each subscnbers line. IR is an in the place of a.

'turely de-energized, causes a relay impulse relay'associated with the junction pertaining to the pre-digit stage and when energized it causes a guarding relay GR to energize; so that it may revent the circuit from releasing during the transmission of impulses. The latter relay'has during this period, a secondary winding which is shortcircuited, thus renderin the relay slow. lCR is'a slowV relay whic energizes during each train of impulses and opens the transmission circuit duri these periods.

MIRis a relay use for metering.

R is the current feedin relay which sup lies talking current to Ate calling subscri er.

This relay cannot be switched into circuit until f the required subscriber has answered. By using a dilerent' relay as the impulse relay i't is possible to employe wider range of sensibility of the latter relay than` when the relays are one and the same.

SIR 'is thecurrent feeding relay for the Vcalled subscriber or station1 and is not normally in a circuit until the called subscriber replies. DR is a differentially wound relay through which the im ulses are' transmitted. It is normally attach to one line branch of the tal circuit exce t duringthe transmission o impulses, w en it is attached to both line branches. It is slow to release and is so connected that it is thrown on a maintaininv circuit 'dependent upon the loop from the called end.

This relay is also responsible for metering 'a Vsuccessful-call to a subscriber, its operations being fully described later. ResistancerR is in the metering circuit, and the ,increase Vof current due to its being shortcirouited causes the subscribers meter to'- o crate.

B R is a relay which, on being rema- R to energize thus giving busy tone to the calling subscriber from BB. BSR when enerized also maintains the guarding circuit so that GR cannot rie-'energize when the circuit is extended to an'operators position.

TGR isa switchin relay,slow to voperate and isused to switc out and in other relays in a manner hereinafter explained.

In Figure 2 CR3 and CR4 are connecting relays. FCR is a relay energized from a selecting device lnot forming part of this invention.

FTR is a relay energized to switch in the ringing circuit and RCR is a relay which is energized when the called subscriber replies and under similar conditions, and which maintains itself in the circuit formed by its second winding. Its operation cuts out FTR the time interval between these operations being utilized t0 send a momentary current over the junction.

In Fi ure 2^ MMR is a marginal relay energize when the current is increased by 'Figure 5.

eicteriorlmeans. This relay,when energized, shortcircuits resistance`R2 thus increasing the current. p

In the case Vof a call to a subscriber, figure 2; would be connected directl)f to Figure 4. The resistance of RCR. in Fidure 2 is such that .SM2 in Flizgure 4: will noi;I be energized. In Figure 3 1R is the calling relay operated 'from the alliugg;V subscribers loop. COlR is a cut fl" relay energized 4by the insertion of the operator-s plug -shown in R is a metering relay enerd when the operator depresses the metermg key MK in Figure 5. RB is a slowreleaserela i which controls the release ofthe circuit. i is suicient to allow theV relays maintaining the .connection to clear.

In Figure 6 the 'relay combinations are d ierent from those of Figure 1 'but the' is a slow release relay which is attached to one line branch and shortcircuteddurng the transmission of impulses. It is operated by a si nal sent over thisline branch when the cal ed subscriber answers or when the circuit is connected to an operators line. TICE. energizes R which m turn enerizes TSR which switches out TKR. Durnigthe time `TKR takes to tall oli, MKB depends for its maintenance on SIR, which may or may not become energized and thus depends u on the establishment of a loop in they succee ing stages.

If a loo be `not established MKB de-energizes be ore TKR and cannot further be energize This will result in the establishment of a clear `line circuit in the connection. Thus it will readily be seen, that if TKR is energized before theA establishment of a loop, a clear linev circuit is established. This is accomplished by an operators circuit Figure 2. The circuit is` for the sake of brevity shown only connected to a special level assi ed. It is clear .that it may be modified to be connected to the final stage as in Figure 3.

In Figure 9 the operation of the circuit de nds upon the cner'g'ization ofsaid rela s Sl, S2R, in a specific order. If S2R 'e ener ed before SIR a clear circuit is establishet'z removing feeding bridges, condensers and the like. l

In an ordinaryconnection SIR is energized during the ringing period and SQR when the culled subscriber answers. MR will in this case energize and bring .about registration. The other relays are similar in action to those described for Figure 1 except that if BSR ever falls ofi.' the connection is totally released back' to the calling subscribcrwho receives busy tone in a known manner.

The functions of the "apparatus shown in e time taken for it to `fall oi 1n shown but operations of the circuit are similar. TKB

Figures 1, 2 and connection with the operation of the circuits which s as follows Circuit 0. When the receiver is lifted, LB is energized.

The method of connecting with an idle trunk forms no part of this invention and may be performed in an known. 'electromechanicalstepping or re ay system; CRI and CE2 connect in the manner described in Patent No. 1,234,610, Betulander and 'Palm'- gren, July 24, 1917.

Circuit l. IR energizes over the extended callers line.

. Circuit 2. GR is energizedover one wind- Ilircuit 3. BSR ener izes over a common impulse selector at the rst digit stage (not described in Patent No. 1162556 Betulander and Palmgren, Nov. 30, 1915.

Circuit 4. COR energizes in circuit 4 completed by GR. SM is biased against this current. CRI and CB2 are held energized in this circuit.

Circuit 4*. GR shortcircuted to make it slow to release. The caller now sends in the,

impulses of the first digit in a known munn'er. When 1 is opened for the first impulse, IR de-energizes. GR beingslow to release maintains the connection.

Circuit 5. ICR energizes and' remains energized for the duration of. a train of 'unpulses. It opens the circuit to the condensers so that they do not interfere with the efficiency of the impulses repeated.-

Circuit 6. IR by back contacts 6 completes a circuit over the trunk to the Ii'rstdigit stage through both windins of the differ- 4 will now be 'described in entially wound relay DR (which is also slow to'release). DR does not energize. IR energizcs at the termination of the impulse. The impulse has thus been repeated tothe first digit stage. At the end of a train of impulses ICR sie-energizes and restores the transmission circuit. The impulses affect circuit changes in a known manner to energizc connecting apparatus, such as CR3 and 0R11, to extend the circuit to another switching stage.

Figure 2 shows thc connection extended to a final switching stage in which CH3 and CR4- have been energized and are retained in an extension of 3, marked 3", the circuit being completed over the common impulse selector apparatus (not shown). BSR thus remains energized.

The selector, represented by relays CRS and CR4., makes connection between trunks, as described in the specifications of Patents Nos. 1162556 and 1195771 Betulander and l'almgren, Aug. 22, 1916.

The caller now sends in the two final trains of impulses to select the tens and units; IR, G and ICR operate as 'before described, and the impulses are repeated over 6. At the termination; of each train Vof: im- I gized and CR5 and CRb retained. Circuit 3*' .for BSR is completed' over FTR andFCR, the latter ,'hav' a retainin winding in this circuit. C 2R cuts o the called partys line relay L2R. SM2 is biased against this current.

Circuit 9. The ringing circuit to call the partyl wanted is completed through a winding of RCR. When the called Cparty lifts his receiver, RCR energizes an loclts up over.8.". '8 being o ned, lTRde-energizes. BSR is maintainede sion'of 3b overRCR.

Circuit 1D. Between the ener@` g of RCR and thel rie-energizing Vof FlR, 10 is completed over one wire of the trunk to' energize DR which retains over-'10".

Circuit 11. SIR is connected to trunk and maintained energized over the called partys line.

Circuit12. SR is energized by SlR and connected to the callers .line over contacts 12 of SR.

Circuit 13. TCR is rst energized over a Contact of DR.

Circuit 13. TCR retainin circuit.

TCR opens circuit 10 of but an alterave circuit 10" for DR iscompleted by Circuit` 14. MR is energized overl: and

retainedover 14. IR'de-energizes. .GR is retained over 2, 2"' and 2". It can only be deener 'zed by a current in the second windin SR c1rcuit'3 is now extended by TC Vover 3".

Circuit 12.*?. Subscribers VS1 and S2 are now connected for talki The power to disconnectthe circuit is in the .control of station S1. If, S2 replaces his receiver, SIR de-energizes, but DR is maintained over, 10. If S1 replaces his receiver 12* is opened and SR de-energizes. il is then com lcted. to shunt resistance-R by second win `n o GR. The increased current in meter `M causes it to register. SM shortcircuits COR and thereby increases the current Ain 4" toda-energize GR.

GR de-energizing opens 3", 4 and 3", causing all relays maintained thereby to deenergize, to restore the Vcircuit to normal.

If the called arty had been engaged, connecting relays CR?, CRS (Figure 4) would not be energized and 3" would not therefore be completed. The final common im pulse selector releasin would open 3, BSR would cle-energize, B energize over 3 to complete 3 to give busy tone to the caller. 10 would not be completed to energize DR 4ene'rgiaed by an exten- 4 and therefore sin, SR, TCR and MR would not be registered. The callerV S1 lacing ize'IR. IR

4'his receiver opens lto lcle-ener opens 2 to de-energi'ze GR w "ch opens 4 to de-energize CRI, CR2 andCQR'tc release the connection.

When a call is olfactive, it may be necessary to release-it `for a trunk or'other special call and the circuitlendsitselffto4 such pos sible clearing although this is not shown.

1R and GR to de- Will de-energize, causing th easing efconnec cner'gizes in series with one winding L4 DR is energizedin 10, as before described:v TCRenergizes over 13. SlR cannotenergize, however, because it is connected in 11 with opposin voltage. DR is Vtliereb'yde`v re-cnergizes ICR over 5*.

energized an TC maintains itself over 13 and causes 1R to des-energize. GR is now maintained over 2", and consequently dependent upon BSR. MR being a mar al relay will not energize in circuit 3*. gille calling line is thus extended to LIR, Fi e 3, over 12; LlR energizing renders t e circuit inac cessible `to other calls in a known manner and flows lamp CL over 15. RR (slow to re ease) is'energized over 8", 8*,

Should the caller replace his receiver before the operator answers, LlR will deen-V ergize and open 15 and circuit 8d. `RR dcener izes slowly so that RCR de-energizing rapi 1 opens 3" to cle-ener and BSR. The circuitisbro en down asbefore described without metering.

If the'call is sustained,' the insertion of the plugfP, Figure gtoanswercompletes acircuitl in which COIR is enfer ed in series' with the shunted lamp CLL de-'ener gizes and CL ceasesftov low. LlR and RR' transfer 8d to 8 and is retained over 17'. P must now be withdrawn to de-energize COlR before RCR can de-cnergize, thus the release of the conection is now controlled by the operator.

The operator answers the call in any known manner. The caller by moving the switch-hook can open 12 without releasing the connection and 4flash lamp CLI in a known manner.

The operator completes the connection required in a known manner and willl meter or refrain from metering as re uired. The withdrawal of the plug or the epression of the meter key will release the connection.

In tbe case of non-metering, the withdrawal of the plug de-energizes CUIR to orlpn `8. BCR de-energizes and opens 3".

e relays maintained in this circuit all deenergize and GR therefore clears down the connection as previously described. RR is slow to deenergize.

In the-case ofthe o erator metering, she gleresses key MK (figure 5 and causes `R to energize over 16". MR switches in 16 and causes the operator-s meter OSM to register in a, well known manner. Resistance R3 is now shortcircuited by 8d, and mm ener izes. This relay shortcircuits resistance Riy 3 and causes to energize. This switches the second windi of GR through 4", thus causing the cal ing subscribers meter SM to energize as before.

TheA current being increased in the second winding1 of GR causes it to fall olf, clearing down t ewhole Vconnection in the manner previously described. The operator then removes the plug. COIR- when energized makes the circuit inaccessible to any further connections in a manner which does not form part of this invention.

In the ca se of the o erators lines being connected to a specie level et an intermediate switching stage, the calling' subscriber will only send in the requisite number of trains of impulses. In such a case Figure 1 will be connected directly to Figure 3 over the first (or second, as the case may be) digit switching stafve. VThe impulse selector pertaining to sai stage will ener ize CR and' CRS as before, land will. switc 3 through to 3d. ,v DR will energize from the earth on LlR as before. SIR and SR will not become energized and4 consequently DR will cle-energize. lCR energizes 'by 1R de-energizing after TCR energizes. It can readily be seen that subse uent operations are exactly as those descri d for an operators connection.

From this it is apparent that Figure 3 represents s. circuit that ma be connected to any level at any digit switc g stage which has no sub nent stage equipped, so that a calling subscriber calling into 'said level will connect with an operators position.

In the case of subscribers calling dead numbers, the latter lines are connected to Figure 12. Figure 12 is a dead number circuit. The portions marked X arc removed from the subscribers equipment and the dotted ortion added when a line becomes dead. y number up to one hundred lines ma be connected to one circuit. A. subscri, r calling any one of, these numbers is connected over Figures 1 and 2 to the rst line equipment of that number and FTBl of Fi re 2 is extended over 8 of Fivure 12 en ener-gizes cut oli relay COR, R and COBB energizes the latter makin the circnitbusy ina known manner. F'I applies ing'current over 1.2al ci Figure 12' but immediately energizes over 9 as described for an operators connection. Now DR of Fi Y e 1 `cannot remain energiged because S1 of Figure 1 cannot ener ize. and, as before, the calling subscribers oop is switched throu h direct, without any current` feeding bri ges to relay LCR. This rela ener zes and closes 18 causin lamp CL to gow. Also .LCR by exten ing 8' to 8' energizes ARR switchin in maintainmxcircuit 19 for relay CO3 he operator actuetes key LK and informs the calling subscriber that the number for which he called has ceased to be e subscriber; LK disconnects 18 and extinguishes GLX. The subscriber maintains the control of the circuit by keeping LCR energized and he may clear at an tune. The replacement ot his receiver wil cause LCR to dei-energize, thus opening 8 and causing ARR to deenergize but too late to prevent RCR of Fi ure 2 de-energizin before 8* is restored RCR will release t e whole connection as previousl described..

When CR de-energizes circuit 18 is completed and interruptor I dashes 1a1npC4 informing the operator of the clearance, and she will immediately restore LK to normal.

The arrangements are not limited to those described ns it is clear that the control of the circuit may be passed to the operator by the addition cf relays such as described for Figure 3.

A local connection will now be described in connection with Figures 6 and 7. The celled subscribers circuit is similar to Figure 4 and need not be specially described again.

When the calling-subscriber lifts, his re; ceiver his line is connected, as described for Figure 1 to trunk Tlat the first up switching stage. Circuit 1 operates l l and completing 2 causes BSR tov energize over the common impulse selector as before de scribed.

GR now energizes over 3, its second winding being shortcircuited over 3. This relay is now rendered independent of- BSR owing to its contact A5 no'w forming part of .3 and BSR maintains itself over 2" and is therefore independent of 1R. COR, but'not SM, now encrgizes over 4. ICR during inipulsing is energized over 5', and removes the condensers from the circuit, whilst the impulses are repeated to the first group selector over 6, TKB is attached to one line 1 branch of the repeating circuit', but is shortcircuited by the selector having an earth connection on the same line branch. TKR is therefore rendered inoperative and can in no way interfere with the impulses..V The first group selector connects. up T1 to T2 as in the case of Figures 1 and 2. The second and third trains ofimpulses operate as be.- foreY and this final group selector energizes FCR over 7, and connects circuit of- Figure 66 as described before,

7 to the called subscriber as before described. BSR is now Vmaintained over 2, FTR and the cut olf relay having become energized over 8 through theconnecting relays, as de- 5 scribed for Figures 1 and 2. FTR .switches on the ringing ,current for the called subscribers line, and whenv he removeshis receiver RCR energizes through the loop over 9. vl RCR cuts out FTB.' as described for Figure 2, lbut during the time the latter relay takes to def-energize, a current'is sent over one line branch, and cnergizcs TKR over 10, this relay holding itself over 11. TKB/also l switches in SIR which ener over the called subscribers loop 412. is ener gized over 13, and then TSR ener s over 14, and holds itselfover 14. j he `latter relay opens 111 and 13 and TKB.' desmer-v gizes. Supposin SIR to .besalso' cle-.enerizcd, MKR wou d cle-energize 4r'st. 'TKR eing a slow releasing relay but if SlR be energized durinv -thetime TR takes to deenergize, then ltCR will be maintained over 13", and thus rendered independent of SIR. This combination is really a testn land metering device, the meter vrelay being" (R which is for o. short space of timel thrown on to SIR in order to test whether the-called subscriber hasansvvferedl4 Tliesaid subscriber may replace his receiver at any subsequent time but metering'will now take place'independently of any action he may talre.L

TSR opens` the shortcircuited winding of GR.

The calling subscriber S1 is now able to speak to the called subscriber S2 over 15. Should S2 replace his .receiver SlR will deenergize with Ino further result.`

Upon S1 replacin receiver,4 1 is opened, 1R de-.energxzes and the4 second winding of GR is now switched over 4 whilst the first winding is ener ized over 3".. Calling(v subscribers meter S energizes, shortciicuitng COR and increasing the current in the second winding of GR causes it to cle-ener ize, thus releasing the entire connection. uring the time S1 and S2 were conversing, if by some external means the retaining circuit 4 were opened, CRl .and CR2 cle-energizing would. cause 1R to deenergize, and thus release GR destroying the connection without causingSMto energize. Similarly, if 2 be opened, BSR will de-energize causing 15 to be established thus giving busy tone-to vS1 and releasing the trunk leading from thefirst switching stage. The caller will clear, causing 1R' to cle-energize, thus de-energzing GR by opening 3 which will release the connection.

Ifv 8* were opened, 'RlCR would cle-energize, and opening2 would de-energize BSR to give busy tone to S1, who would replace receiver Vund cause release without metering Therefore it is clear that'the trunks, withthe exception of that leadingbto. the rst digit sta e will be-released y the vinterruption o. the retaining circuit by a trunk operator, or by en other external means. The calling subscri er replacing his receiver releases the remainder of the connection without Vcausing registration on the calling subscribers meter; This feature is an important part of the invention. Should the called subscriber be engaged with another line when called by S1, CH3 and CRA- would Vin the manner explained for Figure 1 not have become energized and therefore 2 would not have been established. BSR would (ie-energize releasing the outward trunk and establishing 15' i'e 'busy tone to S1.

- TSR, MKR and SlRldo. not in Vthis i'sase become energized and 4* isl therefore ynot established. The replacement of B5 the calling subscribers receiver, opening 1 causes 1R to ile-energize, and 3 being opened GR de-energizesiand o ening 4 releases the connection entirely. T us in Figures 6 and 7. as in Figures 1 and 2 the calling sub- 90 scriber controls the release of the trunk lending tothe first group switching stage on calls made to enga e lines, and controls the release of the wliole connection` unless the said connection be interrupted,l by a. more favoured' connection or by any other means, when, ifthe interruption Ibe beyond the- First group switching stage, the connection is released beyond that stahge, and if the interruption be before the rst group switching stage the connection is entirely released, metering in no case taking place.

A connection to an operators line shown in FigureS will now be described in connection with Figure 6. It is assumed that the said line is connected to the Erst group switching stage, though it is obvious to anyone skilledin the art that such a circuit could be connected at any stage as in the case Vof Figure 3; The irststage of the con- 110 nection has already been described and need not be *rc cated.

The se actors concerned set up the connection, and trimk T1 is joined through to T3. (1R-5 and CRS being energized, `BSR 115 is maintained over 2, (Figures 6 and 8) negative from one line branch over L2R energizes TKB over 10e. MKB. and TSR energize as before; TSR will remain energized,but MKR and TKK will deenergize, the former because SlR does not become energized. A clearv line circuit is therefore established from S1 to [12R over 15", GR being maintained over 3" and dependent upon the maintenance of the ener ization of BSR. L2R energizes and compates 18, causing CL3 to glow, and extends 2 to 2 thus energizing RR which is slow to release. Now S1 may clear bcforethe'operator answers by causing L2R to cle-energize and 130 -emn 2 and 2*.

SRI-fenergizes lbefore RR.

Y given to ripening 2, thus releasing BSR before RR e-energizes. BSR releasing causes GR to denergize, thus opening 4 and entirely relensing the connection without causing metering.

Should the operator answer by inserting a plug 16 energizes COlR and'RR maintems ltself over `17, L2R de-ener izes and extinguishes CL3 while-2' is exten ed to 2f. S1 is now able to tall! to the operator over 12". .Should the o erator desire to meter, she will cause MR to energize as before over 165, thus extending 2*x to 2' and shortcircuiting R1 end'causmg MR (Figure 6) to energize, thus extendinn' 4 to 4?, and so shortcircuiting. resistance L This causes SMto ener ize', registering the call but does not cause E to Vole-energize' and thus the circuit is not cleured down. lfhis is eccomplishe'd by the withdrawal 'of the operetors plug,.opening 16,-when COlR falls ofi thus v1'1" is also (Jpned but .Y r having 3. opened de-energizes and releases the circuit inthe manner previously described. In this case it is seen thatmetering from the operator does not release the connection, but 4it is clear that with a slight modification this couldbeaccomplished as in the case ofFi resland 3.

A ocal connection will now be described in connection with: Figures 9 and l0, and a call to en operator in connection with Figures .94 and 11. For the sake of clearness theo erntors line` is tekenV as being connecte t the first group-switching stage, but Vit-.is'obvicms that it may form partr of an istage, as in the case of Figure 3.`

n Figure 9, the calli-ng subscriber S1 is connected: to, three rela and a meter particular :to his line. L is the line relay, CGR the cut oi yrelay and AR a slow release relay. These relaysvoperate in a manner, which forms no part of this invention being described in Serial No. 101769. SM is the-subscribersmeter to register only effectivel calls in the' manner to be described. S11-on lifting his receiver completes 1 und energizes LR which, as previously explained, causes said subscriber-s line to-be connected to` a-rst group switching trunk'Tl. 2 being completed.. energizes IR; BSR: and ,GR energize. over 3 and 4 respectively, and as pre viousl e described BSR becomesdepenclent on Gli. lThese two relays complete 5.and

A001i energzes cutting out 1 and LR.

AR energizes over 6. It is obvious that if 'BSR or GR- cle-energizes, 5 will be opened endY COR, CRI anclCR2 will vcle-energize. AR will now be energized over 6* through loop` of S1 and busyy tone` from BB will be Si, the connection being entirely released. During the impulsing yeriods, ,IGRenergizes over 7 and the imp es are repeated over 8, SIR and S2R and the conenergized over called. subscribers cut oi relay over 10. SIR energizes over 13 (the negative of SlR being of higher potential than that on contact of FTR; the object of this is that if the ringing be of lon dura.- tion, SlR- will not be heated). 'his is broughtv about for reasons that will become apzarent. 4

TR- also rings the required subscriber over 12, and when he remo-ves his receiver RCR energizes over.v 12 and retains over 10, cutting out FTR which de-energizes. S2R now ener izes over 13 thus energizing MR over 14: w ich maintains itself yover 14, MR ospening the shortcircuted windi voi' GR.

`is now able to talk to the c led subscribe;- over 12,`S1 receiving talking cur-rent from 1R end the called subscriber over S13 and SZR.

If the latter re )lace his receiver, these relays cie-energize hutnothing further happens. Vihen S1 re laces his receiver, v2 be ing opened causes R todo-energize. This extends 5 to 5", shortcircuiting R and causing subscribers meter SM to energize, thus shortcircuiting COR and increasiner the current in the secondA winding of i which causes it to cle-energize, thus completely releasing thc connection by opening all retaininsr circuits.

thould the required subscriber -be engaged at the time of calling,BSR would be de-euergized aspreviously described. 5 beingopen would release the entireconnec-tion and busy tone would b e -giren over 6 as already explained Metering cannot 'take place, because 5"'is never switched in. If the called subscriber does not answer and S1 replace his receiver, IR cle-energizing causes GR to cle-energize, and this opening 5 and 3 clears down the entire connection without metering.

If, when S1 is speaking to the lcalled subscriber, retaining circuit 5 be. opened by a. trunk circuit, CR-l and CB2 will dleenerg'ize, causing the release of the connection without metering. Similarly if 3, 'Smor- 3" be opened for any like reasonBSRwill cle-energize releasing.' the connection without metering. Similarly if 10 be opened end RCR de-energized, en equivalent result is obtained. 4

It isto be noted ,that in such cases the calling subscriber will not take anew trunk leading from the prefselectng stage, yes LR cannot be rie-energized unless he replaceshis receiver und starts a fresh call, as explained in Patent No. 1,225,291, dated May 8, 1.917.

In the case of a. call to the manual board, the call is set up in the seme menner byv S1 and IR 'but trunk T1 is connected to T3.

As before T3 ma be at any group-switching-stage but for t e sake ofclearness is explained'as if it were connected 4at the first digit switching stage. A. 1 to 8 are com leted as before, and' then'BSR is maintain 3'i (F' res 9 and 11). SQR isnow ener# gized fore S111-` over 15, Vand then TSR energizes over 16- and holds itself over 16. TSR removes IRnSlB and S2R from the 'transmission circuit and a cleai-` circuit is established from S1 over 17 to-L3Rand resistance R2, GR maintaining itself incircui't 4- over contacts of BSR and TSR. LBR energl'ilz and CL lows over 18 while 3d is switc edfthroughenergizing i Itis obvious fromthe previousex lanations that if S1 replace llus receiver efore theo rator answers, BSRv 'de-enc'ergize and 'ear down theconnection lwithout caus- 'mg metering j f the operator answer, COlR' energizes over 19 cutting'out LBR and lamp 'OL ceases to glow. RR maintains itself over 20 and 3 is extended Vtol'l. The oplerator can meter by energizing MRR ands ortcircuiting R1, thus causing y (Figui-e9)` to energize. MMBextends 5l to 5, shortci'rcuiting R and causing SM to energize. Clearing can only be accomplished'by the operator withdraw in theplug, as 1n the case of 4Figures 6 an 8.

Figure 14 represents anoutgoingline from an operators osition to the automatic exchange, these es terminating at the first group switching' stage. An operator desiring to establish a connection with an auto matic'subscriber first 'identifies a disengaged junction by observi the condition of the engaged lamps EL. 4he thenV inserts a plug in 'jack J of a disengaged junction. 1 is completed and theusal supervisory signals in the operators cord circuit glow in a well known manner. Resistance Bi. is suchythat relay COZR does not energize.v '12R ener-l gizes over 2,. but the resistance of this relay is such that the supervisory signal of the operators cord circuit remains unchanged. 3 is completed andthe engaginglamps pertaining to the junction taken glow. I2R opens circuit 1 and relayv C021?. energizes over l. BSR energizes over circuit 4 in the manner explained' for Figures l and 2.

It is to be noted'that if this relay de-ener gizes through any cause, BR will energize, effectively preventing the ria-energizing of BSR. The operator sends in the impulses in a well known manner, and these are repeated to the impulse selectors over 5 throughDR, which does not energize. Eventually the junction Tl is connected accord- -ing to Figure 2 to the called subscriber as previously explained. The called subscriber replying, DR energizes over and maintains itself over 6, cuttin out 12R thus establishing a clear circuit om the operators cord to the called subscriber over 8. Should the subscriber be engaged at the time of calling, BSR would'bede-energized thus energizing BR over 7, giving an interrupted 4tone tothe operator setting up the connection. The operatorsV supervisory signals o rate-in a well lmown manner, s' aling tv e'reply-of `the called subscriber. the release of the connection, and this is accomplished by the withdrawal of the lug, which opens l, causing 002B.- to fall o and opening Il.v

Figure 13 represents a similar .junction using a shortcircuited` relay KR of the diii'erential relay DR in Figure-14. The junction J2' joins u withv Figure 7. When e operator controls` a connection is est lished, the operationvof the circuitis as follower- The operator insertingthe iplug in vJ2 completes 1 which energizes I3 thus complatino' 2 `and 2*. Enga d lamps EL glow and IISR energizes as efore. BS'Rcomlpletes 3, energ'lzingGlR, whichv maintains signals of the 4o1; erat `)rs cord circuit behave in the same manner as described for Fi 14. In the case of acall to a busy subscribbli BSR will dsa-energize, thusgivin'g interrupted busy tone to the operator by circuit 7.

What I'olaim is;-

1. In automatic and semiautomaltic tele phone systems, the combination of subscribers lines, battery devices,vdiscrimi mating means adapted in one condition to connect battery feeding devices to the lines of calling and called subscribers,A and to place the control ofthe release of the connection with the calling subscriber, and in another condition to cut oil said device from a calling line, and Ito place the control with an operator, means for altering the condition of such discriminating means, a third conductorcircuit and a relay in said circuit adapted on the circuit being extended to an operator to maintain the partially complete connection against release.

2. In automatic and semi-automatic telephone systems, the combination of subscribers lines, battery feeding bridges, condensers, a pair of relays, one of which is attached to each line branch of a connection, and which are adapted to remove the feedb and is therefore indeing bridges and condensers from the connection, means at the called end of a connection 'for operating the pair of relays, and means for establishing a direct connection between the calling and called subscribers.

3. In automatic and semi-automatic telephone systems, the combination of subscribers lines, battery feeding devices, condensers, a manual switchboard, a trunk line leadinv thereto, means for connectingasubscribeiss line to the trunk line, and means for removing the feeding devices and condensers from an extended subscribers line that has been connected over a trunk to the swliltchboard before the operator answers the ca 4. In automatic and semi-automatic telephone systems, the combination of subscribers lines, battery feeding devices, condensers, n manual switchboard, a trunk line leading thereto, means for connecting a subscribcrs line to a trunk line, means for removing the feeding devices and condensers from an extended subscribers line that has been connected over a trunk to the switchboard before the operator answers the call,

Vand a slow acting relay adapted to be connected in the circuit, and to be operated when a calling line is extended to the trunk line, and means for effecting the disconnection of the circuitduring the time taken by such relay to dc-energize.

5. In automatic and semi-automatic telephone sylstems, the combination of subscribers 'nes, battery feeding devices, animpulse repeating circuit, a dlierential relay connected to such circuit and adapted to be inoperative durin the repetition of impulses but to be operat when a calling subscriber is connected to another subscriber or to an operator.

6. In automatic and semi-automatic telephone systems, the combination of subscribers lines, battery feedin devices, a manual switchboard, a trunk e leadmg thereto and a differential relay attached to said trunk and adapted to be energized when A a subscriber is connected to said trunk.

7. In automatic and semi-automatic telephone systems, tbe combination of subscribers lines, batter feeding devices, discriminatin to connect attery feedm devices to a calling line, a manual switch oard, a trunk line leadi thereto and a diicrential relay attache to said trunk and adapted to be energized when the calling subscriber is connected to said trunk but cie-energized and cut away from said trunk by said discriminating means.

means a apted in one conditionV 8. In automatic and semi-automatic telephone systems, the combination of subscribers lines, impulse senders, a relay adapted to feed current to a calling subscriber, a relay. adapted to feed current to a called subscriber, means for connecting the calling and called subscribers, condensers in the connection and means for cutting away said relays and condensers during the transmission of impulses.

9. In automatic and semi-automatic telephone systems, the combination of subscribers lines pre-selector switches, `di 't selector switc es, a trunk connecting e switches, a device connected to the trunk and adapted to feed current to a call subscriber, condensers connected in sai trunk, two relays, each of which is connected to one line branch of said trunk, adapted to feed current to the called end of the connection and means for energizing said relays according to the class of the connection established.

10. In automatic and semi-automatic telephone systems, the combination of subscribers lines, pre-selector switches, di 't selector switches, a trunk connecting t e switches, a device connected to the trunk and adapted to feed current to a callin subscriber, condensers connected in sai trunk, two relays each of which is connected to one line branch of said trunk, adapted to feed current to the called end of the connection and means for completing a loop through said relays when the trunk is extended 4to a called subscriber.

l1. In automatic and semi-automatic tele` phone systems, the combination of sub scribers lines, a device adapted to feed current to a calling subscriber,V a trunk, two relays. each of which `is connected to one line branch of said trunk,` and means for ener am calle en of said trunk before the complction of the connection.

12. In automatic and semi-automatic tele phone systems, the combination of subscribers lines, a trunk, a device connected to the trunk and adapted to feed current to a calling subscriber, condensers connected 1n said trunk, a manual switchboard, two relays, each of which is connected to one line branch of said trunk, means for connecting the trunk to the switchboard means for encrgizinv one of said relays before the other when tiie trunk has been connected to the switchboard and means for removing said current feeding device, relays and condensers from the trunk.

HENRY JAMES IIERINK.

one of these relays` from the 

